Tuesday, July 22, 2008


The Perseids are coming!

Earthgrazers (above) are the meteors that hit the atmosphere at tangent, and skip across it like a stone on a pond rather than plunge straight to earth. They're bright, flashy, and dramatic. They occur when the radiant is at the horizon, and the earth rotates into the dust cloud. We're in a good spot to catch a few this round.

I just installed my newest toy at the bottom of the page: the Mini Astro Viewer. It's easy to use, though I have to remember that Hawai`i is -10h from UTC time. The full Astro Viewer is more robust & fun.

I already used it to plot out the best time to view the Perseids from the Makapu`u Lighthouse . August 11 Paulo (and his new boyfriend) will be in town, as well as my mec (and his mother) from Paris. I'm hoping I can get a group together and trek out to the lighthouse around midnight.

Techie stuff:

Perseus, the radiant of the shower, will rise just after midnight. This will be the best chance of seeing earthgrazers.

The moon will set just before 2am, though it should be well behind the Ko`oalau and Wai`anae mountains long before then.

The primary peak, based upon the techie sites, should last from 1:30am to 4am Hawai`i Time. Scientists are predicting a zenith hourly rate of 100 meters per hour. There is a possible secondary peak at 6:40am, and a teritary at 11:30 am. Unless the sun doesn't rise we won't be seeing those - and since the radiant won't be at it's zenith until after sunrise we probably won't see the max.

When Perseus is at 30 degrees (2am) only about half the total meteors falling will be visible from here.

/ tech

So the choice is wake up early, when Perseus is closer to the zenith and see more meteorites, or go at midnight when Perseus is rising in the hopes of seeing one or two earthgrazers.

It's an easy choice: midnight at the lighthouse.

Now I just need to find out which of my friends are nature-loving geeks. There must be a few.

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